Limitations
This is a single-center study of MS patients obtained. The generalizability of our results will require a multicenter study where this new parameter can be validated. The study design diminishes the reliability of results from linear regression modeling in this study. Due to the small sample size, we had to use stratification to control for confounding and could account for the effect of diastolic dysfunction on the echocardiographic characteristics. There are significant differences in the demographic profile of the two groups. DMS group had a high frequency of chronic kidney disease and ESRD. We excluded patients with ESRD and hyperdynamic LV from analysis to minimize confounding.
Our study utilized the continuity equation method as an independent standard. The continuity equation valve area in the DMS population was comparable to that of 3-Dimensional MVA in one study.10 The retrospective nature of our study prevented us from using an alternative imaging modality to corroborate these findings, which is a significant limitation.
In the presence of significant MR and aortic regurgitation, our results may not be applicable. Therefore, DMSI should be avoided in the assessment of stenosis severity if there is more than mild MR or AR. Also, VTI can show beat-to-beat variability with irregular heart rhythm. Thus, in the setting of cardiac arrhythmia, DMSI can only be reliable if the average of multiple VTI values is used.
Our study included a limited number of DMS patients with AF. Therefore, our results may not accurately capture the impact of AF on TMPG and transmitral flow, both of which were shown to be affected by AF in RMS patients.25 Given the retrospective nature of the data, the ROC curves shown are the best-case scenario and that association strength may be variable in a larger cohort of patients. Also, there is a lack of validation of these cutoff values.
The presence of at least mild MS on the official echocardiography report was an eligibility criterion for our study. Moreover, some interpreters may avoid calling MS in the setting of MAC since these patients usually have normal-appearing leaflet excursion on 2D echocardiography. Therefore, our subjects might not represent the full spectrum of DMS. It is also a limitation that men were underrepresented in our DMS and RMS groups.